I think it boils down to what table you’re at. If you want to have strictly defined rules, then you build out a table with players that has strictly defined rules that the world and players must adhere to. If you’re all kind of OK with “rule of cool” or hand waving away some things within reason (not so much that you’re just completely going Calvinball with the sessions though I’m sure some people like that as well!) that’s totally fine too.

Ultimately you are all just telling a story together. Anyone who is so angry about someone with a disability in their fantasy world that they are willing to leave the table - to the surprise of the DM and another player who clearly are not on that wavelength - is probably not somebody who is a good fit anyway.

The only critique I could possibly give the DM here is for them to reflect on whether or not they set proper expectations at the table. But frankly (barring critical info that has been left out) this is incredibly petty and a player with any emotional maturity should be able to talk through this and move forward with the group. What a strange hill to die on.